Answer:
Algernon did die in the story. Probably because he became too smart and his mind soon after deteriorated that he couldn't take it anymore.
If I remember correctly, he starved himself to death. Burt's (?) theory was that Algernon knew what was happening to him on some level and decided that he would rather die than go back to being some dumb (if not dumber) mouse.
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Scott0129: not really, Burt was force feeding him, until Algernon died, not from starvation, but from from his brain slowly started to become dumber, dumber and dumber until he forgot how to do EVERYTHING (including eating and breathing) and he died.
pretty sad book if you ask me
Yes, Algernon did die in the story. This is because when Charlie was dancing at the party, some beer fell on the table, and Algernon drank it! So sad.